1. Field of Invention
This invention relates to denture cleansing compositions and to processes for making such compositions.
2. Description of the Prior Art
Denture cleansing compositions are known and generally comprise solids compositions which produce a more or less strongly alkaline reaction on dissolution in water to form a cleansing bath. Tablets have been found to be an acceptable form of presentation for such denture cleansers, facilitating dosage control both in manufacture and use, improving ease of handling from a package point of view, and in storage. Such tabletted compositions clean dentures but do not completely remove accumulations of calculus or tartar.
Known acid-reacting compositions, such as those containing hydrochloric acid, remove calculus or tartar but such compositions cannot be tabletted, require special handling and packaging and are inconvenient in use so that their application to denture cleansing compositions generates many problems in both manufacture and use. Thus, no strongly acid-reacting denture cleansing tablets have yet been successfully marketed.
Austrian Patent Specification No. 264015 suggests the preparation of mixtures capable of dissolving in water to form a cleansing solution having an initial pH.ltoreq.5, preferably pH 1.5-4.5 and containing inter alia monopotassium permonosulphate, a carbonate of sodium and an acid reacting substance including sodium bisulphate or a fruit acid. Further it is proposed that certain of such mixtures be formed into tablets for dissolution in water to form a denture cleansing bath and suggested that the tables may dissolve within 7 minutes.
The disclosure in Austrian Patent Specification No. 264015 does not however suggest how the mixtures are to be handled and, more particularly, how the tablets are to be made on a commercial scale. Indeed the moisture content of the suggested components produce mixtures and tablets which are not storage stable and the tablets take an inordinately long time to dissolve. Further, whilst tablets may be successfully produced by hand in accordance with the prior disclosure such processing is not commercially viable and does not produce a fast-dissolving tablet which can effectively remove calculus and generally clean dentures within ten minutes, a period to which the public has now become accustomed.